Internal-combustion engine.



E. TlLSTONi INTERNAL COMBUSTION ENGINE.

APPLICATION FILED Aua.16,19|s

1,234,825. Patented July 31, 1917.

jso

EDWARD TIL STON, OF LONDON, ENGLAND.

IN TERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

Application filed August .16, 1916. Serial No. 115,224.

To all whom it may concern Be it known that I, EDWARD Tnis'roN, a subject of the King of Great Britain, residing at London, England, have invented certain new and useful Improvements in Internal-Combustion Engines, of which the following is a specification. Y

This invention relates to improvements in that class of four-stroke cycle internal combustion engines in which the cylinder is provided with inlet and exhaust ports at its ends controlled by a valve reciprocating in a valve chest at the side of the cylinder the inlet port also being controlled by the engine piston. I

According to this invention an engine of this type is adapted to compress air in the crank case and is provided with a scavenger port at the same end of the cylinder as the inlet port, the arrangement being such that during induction the inlet port and scavenging port are uncovered and acombustible charge is admitted to the cylinder, whereas at the end of thefiring or explosion stroke the inlet port is covered by the valve and the scavenging port is alone eii'ective, to admit air from the crank case for scaveng ing and cooling purposes.

In the drawings Figure 1 is a sectional elevation of a four-stroke cycle engine according to the invention, and

Figs. 2 and 3 cross sections of the valve chest and cylinder on the lines 22, 33,

Fig. 1.

Fig. 4C is a diagrammatic plan showing the arrangement of four cylinders.

In carrying out the invention in the application to a four-cycle engine as illus trated by Figs. 1 to 3, the cylinder a is provided with an exhaust port or set of ports I) in its side at the upper end above the extreme upper position occupied by the piston c. It has a second port or set of ports (Z in its lower part in a position where they are uncovered by the piston c as it reaches its lowermost position. The second set of ports (Z form the inlet which is thus controlled by the piston c. On the opposite side of the cylinder is a third set of ports 6 also controlled by the piston c and adapted to be uncovered when the piston 0 is in its lowermost position. The third set of ports communicate with the crank chamber f, for example the cylinder a has an extension at which passes into an upper extension 9 on Patented July 31, 1917.

the crank chamber f so that an annular space it exists between it and this extension 9', forming a passage for scavenging air from the crank chamber f to the third set of ports 6. a

At the side of the cylinder at and prefer ably in the same casting therewith is a tubular valve chest 2' in which a piston valve 70 slides. The upper part of the chest forms the exhaust passage into which the exhaust ports lead and the interpenetration of the cylindrical chest 71 and the upper part of the engine cylinder a enable large exhaust ports 6 to be provided as is clearly shown in Fig. 2. The upper end of the chest 5 may be closed by a screwed plug Z and a branch m may be provided for connection to an exhaust pipe, whereas in engines for aero planes the plug Z may be omitted and the end of the chest may be left open, and the chest need not project so far beyond the head of the cylinder.

The piston valve is preferably comprises a hollow cylinder the diameter of which is about half that of the engine cylinder. At

the lower end it is fitted with an extension 0 ports or sets of ports are formed one an inlet port 7' from the carbureter and the other an air inlet 8 for the crank chamber. The upper port 9" namely the fuel inlet, is controlled by'the piston valve is while the lower port 8 namely the air inlet for the crank chamber f, is controlled by the short piston or extension 9 on the piston valve. The admission of air tothe crank case may be effected by an automatic or mechanically operated check valve in known manner. if desired.

I The piston valve 70 and its extension q are reciprocated by a crank disk I? and connecting rod u from a half time shaft 2: driven off the engine shaft 2 by a train ofgearing 10, 13,111. The shaft 11 is preferably centrally below the axis of the piston valve 7c so that the angle through which the crank pin passes in the lowermost part of its path ,the piston descends.

the pin is passing over this part of its path. In Fig. l the path of the crank pin is shown divided into four parts I, II, III, and IV, over which the pin is passing during the periods of inlet, compression, explosion and exhaust, respectively,

The cycle of operations is as follows Assuming the piston c has just reached the top of the exhaust stroke, the piston valve is will b-e traveling upward and have just closed the exhaust port 6. The piston 0 willthen descend and a partial vacuum will occur in the cylinder a above the piston 0. Then the piston c nears the end of its downward stroke the inlet ports CZ will be uncovered by it. Consequently a charge of 'caibureted air will enter the cylinder at and fill it. On the next upstroke of the pisten '0 this charge will be compressed, as the exhaust ports I) will still be covered by the piston velvet. When the iston c completes its compression stroke, ignition occurs and In due time the piston valve it also descending, uncovers the exhaust ports 5 in the cylinder and closes the inlet port 1 to the valve chest '5 and the inlet ports d in the cylinder. Consequently, as the iston *0 reaches the end of-the explosi'on stroke the scavenging ports 6 only are effective at the lower end of the cylin der, and the air, admitted to the crank chamber f by the air inlet port 8 controlled by the extension piston Qon the piston valve it), and compressed in the crank chamber f by the descent of the piston '0, enters at the lower end of the cylinder and scavenge's the cylinder at from that end upward to the exhaust ports 6 at the top. The piston Q then ascends and completes the expulsion of burnt gases from the cylinder and the cycle is repeated.

\Vhen 'a number of cylinders a are arranged on the same crank shaft as indicated in Fig; at, the crank case 7 is divided by partitions 5 into; separate compartments, one for each cylinder.-

I claim 1. An internal combustion engine comprising' a crank case, a cylinder, apiston reciprocating therein, and a valve chest 'adjacent to said cylinder, said cylinder having an exhaust port at one end in a position beyond the limit of each inward stroke of said piston and communicating with said valve chest, and an inlet port at the other end adapted to be uncovered by the piston as it nears the limit of each outward stroke, said inlet port also communicating with said valve chest, a reciprocating valve in said valve chest for opening and closing said exhaust port and said inlet port, the said cylinder having a scavenging port at the'same end as said inlet port and also adapted to be uncovered by the said piston at the end of its outward stroke, said scavenging port communicating with the crank case, means for admitting carbureted an" to said valve chest in a position close to said inlet port, means for admitting air to said crank case, and rneans for reciprocating said valve in synchronism with the said piston whereby at the end of the induction stroke of said piston the said inlet and scavenging port are open for the purpose of admitting earbureted air and air to the cylin'der, whereas at the end of the hiring stroke the said inlet port is closed by the said valve but the scavenging port is open for the pur= pose er admitting air for scavenging and cooling purposes, substantially as herein-' before's'e't forth. i

An internal combustion engine comprising a cylinder, a piston reciprocating therein, a valve chest adjacent to said cylin der, a pistonwalve in said chest, said cylinder having an exhaust port at one end in a position beyond the limit of eaeh inward stroke of said piston and communicating with said valve chest, and an inlet port at the other end adapted to be uncovered by said piston as it nears the limit of its out ward stroke, a, crank case having an air inlet port, an extension on the aforesaid pis ton-valve for opening and closing'said port, the aforesaid cylinder further having a scavenging port communicating with said crank case and adapted to be uncovered by the aforesaid piston at the end of its the ward stroke, and coeperating cranks connected to said. piston and the extension of said piston-valve, said cranks being eentral in relation to the piston and extension respectively, substantially as and for the V purpose hereinbefore set forth.

In testimony whereof I have signed my n'ameto this specification in the presence of two subscribing witnesses.

A. W. MATHYs, H. Mami copies of this patent may be obtained for five cents each, 1 y addressing the commissioner of Eaten,-

' Washington, D. 0.? i 

